If the texts are all coming from a single number (or at least appear to be) you can try to block that number, though these sorts of junk texts often come from spoofed or multiple numbers and so cannot be blocked. If you can identify the campaign that's sending these messages, you could try to contact them and get them to take you off their call list, though I doubt very much that would be effective. Or depending on the country you're in and its laws regarding sending unsolicited texts, you could report the campaign to your country's communications authority.
Other than that, all you can do is get a new phone number.
Regards.